Treatment for improving bituminous coal



Patented Nov. 3, 1936 PATENT OFFICE TREATMENT FOR IMPROVING BITUMINOUSCOAL Joseph C. Nelms, East Cleveland, Ohio No Drawing. Application July31, 1934, Serial No. 737,779

5 Claims.

This invention relates to a treatment of coal which has for one of itsprincipal objects the prevention of the accumulation of soot in the firebox and fiues or stack of the burner.

More specifically, by reason of the fume or vapor, the material used inthe treatment, causes a burning and combustion of deposits therefromsuch as the soot; and further, the soot formations resulting from theburning of my treated coal ignite at lower temperatures than soot fromlike untreated coal.

This invention particularly relates to a treatment of bituminous coal,and it is an object of the invention to effectively so treat bituminouscoal that the accumulation of soot shall be very little.

By comparison it is as little or less than that resulting fromsemi-bituminous coal such as Pocahontas coal.

A further specific object of the invention is to cause a material changein the temperature at which the soot ignites, so lowering it as to causeits burning at low temperatures.

A further specific object of the invention is to cause thesoot-preventing chemicals to adhere to the coal by a material whichshall be substantially water-proof, thus resisting weather, and whichshall be non-corrosive in its nature thus avoiding corrosion of therailway cars or bins in which it may be mixed or stored.

A more specific object is to so treat the coal that the final productshall be substantially dustless.

A resulting advantage from the use of my treatment is that of reducingthe fire hazard by preventing large accumulation of soot due to the factthat the soot ignites at temperatures several hundred degrees lower thanthose usually required to ignite the soot from bituminous coal.

In extensive tests'and experiments over a considerable period of time,it had been found that common salt heretofore attempted tobe used toreduce soot deposits, could not be retained upon the coal by the use ofcommon waterglass for the reason that the salt caused decomposition anda sediment formed in the solution before it could be applied.

The commonly known treatment of coal by the use of zinc to preventformation and reduce soot or tocause an ignition of the soot previouslydeposited, was not of itself sufficient to accomplish substantialresults.

The effectiveness of common salt and zinc, however, if they could beretained upon the coal by a moisture or waterproof binder, becameapparent. Many of my experiments demonstrated that by using certainsodium silicates in which the alkali content was great in proportion tothe silica, namely the ratio of NazO- to SiOz was very high, salt couldbe retained in certain proportion, but, the resulting residue on thecoal after the water evaporated was not waterproof, however, if commonwaterglass is used therewith the mixture will effectively retain thesalt in solution and render the coal waterproof and dustless.

Numerous tests resulted in the discovery that about sixty percent of thesodium silicate should be common waterglass, and forty percent should bethat of high alkali content. In the chemical trade, common water glassdenotes a material of about 40 Baum and has a proportion of sodium oxideto silica of a ratio of approximately one to three, respectively. Thehigh alkaline water glass denotes a proportion of sodium oxide tosilicon dioxide of a ratio of approximately one to two, respectively,which produces the material averaging a density of about 59.1 Baum.

This mixture retained the common salt and at the same time rendered theproduct substantially waterproof, thus avoiding the removal of theeffective chemicals, as for example when exposed to rain. If largerquantities of the high alkali content silicate are used there is stillless danger of precipitation, but the material more readily washes offfrom the coal.

Such a material applied to the coal results in lowering the ignitiontemperature of the soot from bituminous coal from say around 1200 F. toabout 1000 F. For example, the application of such mixture as 14 fluidounces of waterglass and 8 fiuid ounces of high alkali sodium silicateto one gallon of water with 1 pounds of salt, and 8 ounces zinc dust,mixed and used in sufiicient quantities that when sprayed upon about oneton of coal it will cover the same, results in effectively clearing thefire box and pipes of various types of furnace and stove burners.

I have found that a further addition, namely of black copper oxide (CuO)in proper quantities increases the efficiency as a soot preventive.However, if too much was used, a dense soot was caused which did notreadily burn. If too little was used, a higher temperature was requiredto ignite or burn the soot out of the pipes. The addition of aboutone-quarter pound of black copper oxide to each ton of treated coal wasfound to be most eificient.

I prefer to first mix with each gallon of water 14 fluid ounces ofwaterglass, 8 fluid ounces sodium silicate having a very high alkalicontent. I then add in proportion to each gallon of water,

1 pounds of salt, 2 ounces black copper oxide and 4 ounces of zinc dust.I find that to thoroughly cover the coal about 2 gallons of this mixtureor somewhat less, is sufficient.

A further result found from actual use of my treated coal, that is,actual burning of the coal, is that of the ignition temperature of thesoot was lowered materially, and the residue remaining in the pipesafter the ignition of the soot consisted largely of fine coal ashcontaining a small quantity of sodium chloride and copper and zincoxides, with only a negligible quantity of combustible matter, i. e.soot. This residue occurring in the pipes aids the almost completedremoval of soot when the burning takes place, and in fact it appears tohave an insulating efiect upon the pipes. The quantity of residue doesnot increase after a given time, there being a sort of equilibriumestablished at the time when the soot blows away at about the same rateit is deposited.

So effective is the material of my treatment that soot formed in largequantities by the burning of very poor bituminous coal, yard scrapings,and so forth, in a heating plant, was efiectively if not entirely burnedaway by the use of but a few pounds of coal treated with my formula.This was by temperatures no greater than a moderate fire. Thereafter theburning of coal so treated results in the deposits being minimized andsuch soot deposit as does occur is subject to burning ignition at around800 F.

This latter point is of importance in that by the burning out of fiuesat such low temperatures and of such small quantities of soot, the firehazard is greatly reduced, or largely eliminated.

As to the corrosive effect of the compound used on the coal, I havefound that not only does this not aid corrosion but evidently has aproperty of functioning as a rust-preventive. The corrosive action ofthe sodium chloride or common salt is apparently oil-set andcounter-acted by the protecting film action of the sodium silicate.

The use of my treatment makes possible the control of smoke,particularly because of the clear fiues whereby the air may be moredefinitely controlled.

Coal treated by my process may be burned in heaters not designed forbituminous coal or coal of high content of volatile matter. In ordinaryhome furnaces and stoves there is no provision for the effectivecombustion of volatile gases, thus attempts to use soft coal, or coke,in a furonce in a house or in household heaters results in excessivesoot and smoke. By my invention the soot nuisance and difficulty iseliminated and one is thereby enabled to regulate the quantity of air tothe heater which enables the burning of the volatile gases instead ofallowing them to form soot and smoke.

For example, if the content of the fiue gas-es is maintained so that 15percent of carbon dioxide (CO2) is present, even with clean fiuesconsiderable smoke is evolved, but if enough air is admitted to the fireto reduce the content of carbon dioxide to 10 percent, no more smoke maybe observed than when using semi-bituminous coals such as Pocahontas,particularly if burned under the same conditions. Thus the ordinaryhouseholder is enabled to not only eliminate soot and reduce smoke, buthe is permitted the use of very much cheaper bituminous coal for heatingin place of the expensive semi-bituminous (Pocahontas) or like coals.

By this invention the ordinary householder is also enabled to use clean,dustless, moisture-proof coal, having the foregoing advantages.

Having thus described my invention, what I claim is:

1. A process of treating ordinary coal comprising mixing with 1 gallonof water, 14 fluid ounces of sodium silicate having a ratio of sodiumoxide to silicon dioxide of about one to three, respectively, 8 ouncesof sodium silicate having a ratio of sodium oxide to silicon dioxide ofabout one to two, respectively, 1 pounds of salt, and applying the sameevenly to the mass of coal to form a thin coating thereon.

2. A process of treating ordinary coal comprising mixing 28 fiuid ouncesof sodium silicate having a ratio of sodium oxide to silicon dioxide ofabout one to three, respectively, 17 ounces of sodium silicate having aratio of sodium oxide to silicon dioxide of about one to two,respectively, 3 pounds salt, and one-quarter pound copper oxide andsuiiicient water to permit applying the same evenly to approximately aton of coal.

3. A coating for coal, adapted to prevent a formation of soot as aresult of combustion and to render the coal substantially dustless,comprising salt and a plurality of sodium silicates, one having a veryhigh alkali content, the other being common waterglass, the quantitybeing of substantially the same or of less weight than the combinedsilicates.

4. A coating for coal consisting of salt, black copper oxide, waterglasswhich is ordinary sodium silicate, and sodium silicate having a highalkali content, the latter being approximately two-fifths of the amountof the waterglass.

5. A coat adapted for use on a bituminous coal and consisting of thefollowing ingredients and amounts for each ton thereof; three pounds ofsalt, one-quarter pound black copper oxide, onehalf pound zinc,twenty-eight ounces of common water glass, and about seventeen ounces ofsodium silicate having a high alkali content.

JOSEPH C. NELMS.

